getInternalId

Provides a common getter for the persistence layer to obtain an identity,
irrespective of the actual type of identity used.

Typically a subclass will delegate to a public
SomePrimitiveWrapper getId() method. The necessity for the
getInternalId() abstract method is solely because the
persistence layer needs a way of obtaining the identity irrespective of
the actual identity implementation choice.

Returning null from this method will indicate the object has
never been saved. This will likely be relied on by some DAO
implementations.

shouldExecuteSessions

Note: if load balancing is disabled for this agent, that method will always return
true. If load balancing is enabled, that method will return true
if and only if this agent is itself referenced as load balancing agent.